Nest Thermostat - Trane TR90 - TCON802AS32DAA

[dwmales]

Hello and thanks for any suggestions offered. Recently purchased a Nest Thermostat and encountered what appears to be  fairly common issue: error code N260 - your thermostat needs a C wire. I have a TR90 (single-stage) furnace and a TCONT802AS32DAA thermostat. The existing 5 wires (yellow not used) are connected to the backplate as follows:

RC-R: Factory installed jumper

Red wire-->R

White wire-->W1

Green wire-->G

Black wire-->B

I wired the Nest Thermostat as follows:

Green Wire-->G

Red Wire-->R

White Wire-->W

Black Wire-->0B

This is when I get the N260 error. I moved the black wire to C (common?) and still had the same @N260 error. Do I require the Nest Power Connector to remedy this problem? When I take the batteries out of my Trane thermostat and reconnect, it does not work. Does this suggest that it too is not getting power?

[Patrick_Caezza]

@dwmales 

Post a picture of the original thermostat's wiring here.

Trane uses the B terminal as the C wire so the black wire should be connected to the C terminal on the Nest.

[dwmales]

Yellow wire not used.Trane Thermostat Wiring DiagramNest Thermostat Wiring Plate

Thanks @Patrick_Caezza

[Patrick_Caezza]

@dwmales 

That's it

[dwmales]

Thanks for your help @Patrick_Caezza, much appreciated. I did try moving the black to the C terminal on the Nest thermostat and I continued to receive the same N260 error code.

[Patrick_Caezza]

@dwmales 

Try resetting to Factory defaults and set it up again.